In this paper, a non-isolated buck-boost single-inductor multiple-output (SIMO) DC-AC inverter for driving multiple independent high-frequency AC outputs of medium power, is proposed. Compared with traditional bridge-type inverters, the proposed buck-boost SIMO inverter achieves (i) a smaller component count, (ii) fully independent power control of its outputs, (iii) better scalability in increasing the number of AC output channels, and (iv) higher power efficiency. Operating in pseudo-continuous conduction mode (PCCM), the rated power of each output channel of this inverter can be high while attaining zero cross-regulation. The scalability factor of the proposed inverter is formally investigated and the theoretical maximum number of AC outputs is analytically derived. The targeted application of the proposed inverter is for driving multiple transmitter coils to realize versatile multi-device medium-power wireless power transfer. A hardware prototype of a single-inductor three-output (SITO) buck-boost inverter delivering a medium power of 8.4 W per output channel has been constructed. It is experimentally verified that precise and independent current regulation of individual transmitter coil is achievable with the proposed inverter.